Q1: It seems like this year  the solemnity of the Immaculate Conception is transferred to December 9, Monday. So, we have a kind of double obligation. (I know that in some countries bishops lift the obligation in such cases, but not in my country.)
But on December 8 I’m going to attend the Traditional Latin Mass, where, according to the 1962 rubrics, the feast of the Immaculate Conception outranks the 2nd Sunday of Advent and stays on December 8. December 9 is then a feria. What are my obligations in this case? –Maksim
Q2: I am canonically Roman Catholic, but regularly attend a Ruthenian Catholic parish church. I originally thought that I would have to still conform to the Roman Code of Canon Law, but the pastor of my church told me that if I wanted to be byzantine rite, I have to only follow the directives of the Eastern Code of Canon Law and the Ruthenian Bishop and that I can’t try to do both. Is this true? I’ve been following his instructions for the past 3 years but reading some articles, I’ve seen it suggested that I am still bound to obey the Latin Code of Canon law and am supposed to attend liturgy on Roman days of obligation. I am genuinely confused on how I am supposed to proceed in both of these matters. –Colin
A: The Church’s basic rules regarding Mass attendance on holydays of obligation are actually quite straightforward, and are laid out in “Holydays of Obligation, Part I”: Canon 1246.1 provides a list of holydays on which, in addition to every Sunday of the year, Catholics are obliged to attend Mass (c. 1247). But as we saw in the article just cited, Episcopal Conferences can (and often do) suppress certain holydays or transfer them to a Sunday, with Rome’s approval (c. 1246.2; see “Are Catholics Supposed to Abstain From Meat Every Friday?” for more on what an Episcopal Conference is).
But for both of the above questions involving holydays of obligation, the issue is slightly different. Each of our questioners knows which days are holydays; what they’re struggling with is knowing which liturgical calendar they are supposed to follow. Let’s look at the second question first.
Colin’s situation highlights the distinction between the Latin Catholic Church (which comprises the overwhelming majority of Catholics worldwide), and the Eastern Catholic Churches. In “Are They Really Catholic? Part I,” we saw that not all Catholics are Roman (i.e., Latin) Catholics. Depending on how you count them, there are actually about twenty different groupings of Catholics on earth today—and the Ruthenian Catholic Church mentioned by Colin is one of them. These different groupings of Catholics are known in technical parlance as Catholic Churches sui iuris. (Note that this is not synonymous with a rite—see “Adopting Children of Another Faith (Eastern Churches, Part II)” for more on this.) Most of them exist today because in centuries past, significant numbers of Orthodox clergy and faithful returned to full communion with the Catholic Church.
Since Eastern Catholics are truly Catholics, they share the same faith, the same sacraments, and the same governance as Latin Catholics (cf. c. 205). Thus there’s no reason why a Catholic who is a member of one Church sui iuris couldn’t attend Mass at the parish church of a different Church sui iuris to satisfy his Sunday obligation. After all, we’re all Catholic!
And this is exactly what Colin says he has been doing. A member of the Latin Catholic Church, he attends Mass and receives the sacraments at a parish of the Ruthenian Catholic Church. There’s absolutely nothing wrong with this; but as was already discussed in “Why Don’t We Marry Validly Before a Ukrainian Catholic Priest? (Eastern Churches, Part I),” attendance at the parish of a different Catholic Church sui iuris does not make you a member of that Church. Rather, our membership in a particular Church sui iuris is determined—assuming we were baptized as Catholics while still infants—by the Church sui iuris of our parents (cf. c. 111.1). Colin may very well have been attending the Ruthenian Catholic Church all his life; but if his parents were Latin Catholics, then he is too—and involvement in a Ruthenian parish church does not alter this fact.
It’s only logical to conclude, therefore, that if you’re a Latin Catholic, you are bound by the Code of Canon Law, which pertains to Latin Catholics (c. 1). Members of the Ruthenian and other eastern Catholic Churches sui iuris actually have their own canon law, which to a large extent is identical with the Latin code but also contains quite a few canons which are different, reflecting the specific history and traditions of the eastern Churches. Eastern Catholics have their own holydays of obligations which they’re obliged to observe—although a few holydays, like Christmas and the Assumption of the Blessed Virgin Mary, are common to all the Catholic Churches sui iuris, whether Latin or eastern.
Returning to Colin, we’ve seen that although he regularly attends a Ruthenian Catholic parish, he himself is a Latin Catholic, not a Ruthenian Catholic. Thus he is bound to observe the Latin Catholic Church’s holydays of obligation, regardless of the fact that he doesn’t regularly attend Mass at what is technically his parish. (As was discussed at length in “Parish Registration,” canon 518 tells us that parishes are territorial, and therefore Colin’s actual parish is determined by his home address.)
Colin says that “the pastor of my [Ruthenian Catholic] church told me that if I wanted to be byzantine rite (sic), I have to only follow the directives of the Eastern Code of Canon Law and the Ruthenian Bishop.” But as we saw in “Becoming (Or at Least Marrying) an Eastern Catholic,” this is categorically false. Simply deciding to follow the laws of a different Catholic Church sui iuris most certainly does not magically make you a member of that Church!
Since Colin was acting in good faith, it’s hard to argue that he is morally culpable for failing in the past to attend Mass on those holydays of obligation observed in the Latin Church. The only arguable culpability here would be that of the Ruthenian parish priest, who surely knew better than to give such erroneous information to a member of the faithful! Now, however, Colin understands the real requirements, and so there will be no excuse if he neglects these obligations in the future.
Let’s turn now to Maksim’s question. A Latin Catholic, Maksim understands that he is obliged to observe the holydays of obligation in his Latin diocese. This past year, since the Feast of the Immaculate Conception fell on a Sunday, the Church in his country declared that the feast—and thus the obligation to attend Mass on that feast—was transferred to the following day, Monday, December 9. This meant that all the Latin Catholics of that nation were required to attend Mass on December 8 (because it was Sunday), and then again on December 9 (because as the Feast of the Immaculate Conception, it was a holyday of obligation).
So far, so good. But what happens if you attend the Traditional Latin Mass, a.k.a. the Extraordinary Form of the Roman Rite? The answer is quite simple: nothing.
As Maksim points out, under the old calendar, which was always followed when the Traditional Latin Mass was the norm throughout the entire Latin Catholic Church, the Feast of the Immaculate Conception “outranked” Sunday. For that reason, if the feast happened to fall on a Sunday, the priest celebrated the Mass of the Immaculate Conception, and not the Mass of that Sunday. Many Catholics understandably but wrongly think that when you attend Mass celebrated according to the Extraordinary Form, all the liturgical rules and laws that were in force in years gone by—like this one—are to be followed once again. (See “Are Women Required to Cover Their Heads in Church?” for more on this.) But in actual fact, while Catholics may regularly attend the Traditional Latin Mass, they are still under the authority of their current diocesan bishop, and are obliged to observe the holydays of obligation as they are laid out in their diocese.
Put differently, within the Latin Church sui iuris it’s often possible to celebrate/attend Mass in two different rites: the Novus Ordo, and the Extraordinary Form. Regardless of which Mass a Latin Catholic chooses to attend, he is still a Latin Catholic—and is still required to obey the diocesan bishop of the Latin diocese in which he resides.
It definitely can happen (and sometimes has) that a diocesan bishop, or even the Vatican, might specify an exception to this or that liturgical norm for those celebrating/attending the Traditional Latin Mass. But unless that exception has been clearly stated by the competent authorities, a Latin Catholic must follow the rules of his diocesan bishop, no matter which rite of Mass he attends.
Maksim tells us that the bishops of his country (presumably meaning the Episcopal Conference) declared that in 2019, the Feast of the Immaculate Conception was transferred to December 9. They are bishops of the Latin Church, and Maksim is a Latin Catholic, so he was required to observe December 9 as a holyday of obligation. If he chose to attend the Traditional Latin Mass, that doesn’t change his obligation—he still had to attend Mass both on Sunday, December 8, and on the following day.
As was true in Colin’s case, if Maksim honestly didn’t understand how this worked, and failed to attend Mass on December 9 because he sincerely believed that he was not required to do so … it’s difficult to conclude that he was at fault in a moral sense. Now, however, he has the answer to his question, and so henceforth he knows he must follow the liturgical calendar of the Latin diocese where he lives—regardless of which rite of Mass he attends.
There’s no question that this can get confusing, particularly when we Catholics attend Mass celebrated in either a different Catholic Church sui iuris, or in a different rite! The key is to remember who our diocesan bishop is—and to follow the rules for holydays of obligations as he and the other bishops of his Episcopal Conference have set them out.